1. Field of the Invention
The invention relates to a heat-assisted magnetic recording head and a heat-assisted magnetic recording apparatus, and particularly to the heat-assisted magnetic recording head and heat-assisted magnetic recording apparatus that may reduce manufacturing processes and attain high density and high-speed recording.
2. Description of Related Art
In a hard disk drive (HDD) using a magnetic recording layer, high density recording has been achieved at a ratio of 60% per annum for several years by applying a magneto-resistive sensor which utilizes a magneto-resistive effect, that is, an MR (Magneto-resistive) sensor or GMR (Giant magneto-resistive) sensor (hereinafter both are referred to as “GMR sensor” collectively) and improving their performances.
However, it has become clear that the aerial density of HDD has a limit of about 40 Gbits/inch2 due to the Super Para-magnetic effect, that is, the effect that the direction of magnetization in a magnetic domain is reversed to the opposite direction with the adjacent magnetization and thermal fluctuation, (on page 322, T. Rausch, Trans. of MAGNETICS Society of Japan, Vol. 2, 2002). After that, though the recording density has been improved to more than 100 Gbit/inch2 by enhancing the anisotropy of the magnetic material, the density seems to approaching at last its limit given with the Super Para magnetic effect.
The heat-assisted magnetic recording has been proposed by Japanese Published Unexamined Patent Application No. 2003-45004 as an effective technique for solving the above.
In the heat-assisted magnetic recording head, a semiconductor laser (or optical waveguide), a thin film magnetic transducer and a GMR sensor are stacked, wherein magnetic recording is performed with reducing the magnetic cohesive force of a magnetic medium by irradiating a laser beam from the semiconductor laser to the medium and applying a magnetic field to the medium with the thin film magnetic transducer. Thus, the reversal of magnetization in the recording medium at the room temperature can be prevented as the recording is performed to the magnetic medium having a high cohesive force in the room temperature.
In this system, the recorded part should be cooled rapidly after recording. If not, the recoding would be erased with the subsequent magnetic field having the opposite magnetic direction. Accordingly, the both the magnetic field distribution and heat distribution must be sharp, and be placed together as closely as possible.
The heat-assisted magnetic recording head conventionally proposed, however, has the problem that, the stacking process is long and complicated, resulting in difficulty of reducing its cost since the semiconductor laser must be stacked in addition to the transducer and the GMR sensor. Further, the problem encountered is that high density recording is not achieved because a small recording mark cannot be always formed which size is equal with that of irradiated light spot, and the recording speed would be reduced since it is difficult to align the light-irradiation position to the magnetic field application position.
Further, a system has been proposed, in which a heater is provided on the opposite side of the GMR sensor to the thin film magnetic transducer, and an electric current is applied to the heater to perform heating. In this case, though adding of only a comparative short manufacturing process of the circuit to the conventional process will be sufficient, the problem that the difficulty of making the temperature distribution coincides with the magnetic field distribution remains yet.